The International Patent applications WO99/57118 and WO02/05616 describe 6-phenylphenanthridines as PDE4 inhibitors.
In the International Patent application WO99/05112 substituted 6-alkylphenanthridines are described as bronchial therapeutics.
In the European Patent application EP 0490823 dihydroisoquinoline derivatives are described which are said to be useful in the treatment of asthma.
The International Patent application WO00/42019 discloses 6-arylphenanthridines as PDE4 inhibitors.
The International Patent application WO02/06270 discloses 6-heteroarylphenanthridines as PDE4 inhibitors.
The International Patent application WO97/35854 discloses phenanthridines substituted in the 6-position as PDE4 inhibitors.
The International Patent applications WO2004/019944 and WO2004/019945 disclose hydroxy-substituted 6-phenylphenanthridines as PDE4 inhibitors.